A closer look at the interlayer performance of the waterborne epoxy resin emulsified asphalt adhesive layer material!

Summary

Aiming at the problem of shear stress damage between the asphalt pavement or bridge deck pavement, the water-based epoxy resin modified emulsified asphalt is used as the adhesive layer material.

Key words

Road Engineering | Waterborne Epoxy Resin Emulsified Asphalt | Shear Strength | Tensile Strength

introduction

Whether it is the refurbishment of old roads or bridge deck paving, the performance of the adhesive layer material is one of the most important factors that determine the durability of the road [1-5] coating online coatingol.

Waterborne epoxy resin has excellent bonding properties and is widely used in bonding agents, composite materials, coatings, etc.

Raw materials

Esso 90# road petroleum asphalt is used as the base asphalt of emulsified asphalt

The technical indicators of the water-based epoxy resin used in this research are shown in Table 3

Test plan

Preparation of adhesive layer materials

When preparing the base emulsified asphalt, first heat the base asphalt to 40°C~150°C to make it in a fluid state; meanwhile, prepare hot water at a temperature of 80°C, and control the pH of the aqueous solution to 2~3 by adding hydrochloric acid; The 1.

Preparation of test pieces

In the test, two composites of "5cm cement concrete slab (surface roughening), adhesive layer material, 5cmAC-10 asphalt mixture" and "5cm cement concrete slab (surface smooth), adhesive layer material, 2cmUTFL-13 asphalt functional layer" were formed.

Shear test

The shear test uses the HS-SSI direct shear instrument independently developed by the New Pavement Research Institute of Chang'an University, and its technical indicators are shown in Table 4

Pull test

The drawing test was carried out using the LGZ-1 drawing instrument independently developed by the Highway College of Chang'an University, and the drawing rate was 5mm·min^-1

Indoor test results and analysis

Smooth shear test between layers

In this paper, a UTFL-13 asphalt functional layer is added on the smooth cement concrete to simulate the super-thin asphalt functional layer on the old cement concrete road surface

The following conclusions can be drawn from Figure 2

(1) Within the test temperature range, the shear strength of water-based epoxy resin emulsified asphalt increases continuously with the increase of the content of water-based epoxy resin, and both are greater than the shear strength of ordinary emulsified asphalt and modified emulsified asphalt

(2) The water-based epoxy resin improves the shear extreme displacement of the adhesive layer material

(3) Temperature is one of the important factors affecting the shear strength, and the shear strength decreases sharply with the increase of temperature
.
Under the condition of 60℃, although the shear strength of waterborne epoxy resin emulsified asphalt is greatly reduced, it still maintains a relatively high level (≥0.
195MPa) compared with ordinary emulsified asphalt and modified emulsified asphalt
.

To sum up, whether it is at low temperature, normal temperature or high temperature, waterborne epoxy resin can significantly improve the shear strength and shear extreme displacement of emulsified asphalt, and its shear performance is uniform within the test dosage range.
It is better than ordinary emulsified asphalt and modified emulsified asphalt
.
According to the test results, the recommended content of water-based epoxy resin is 10%~20%
.

In order to study the comprehensive effect of water-based epoxy resin on the shear resistance and plastic properties of the interlayer material, the product of the shear strength and the corresponding shear extreme displacement is used as the viscosity evaluation index of the adhesive layer material, as shown in Figure 3
.

It can be seen from Figure 3 that the product of the shear strength and the corresponding shear extreme displacement of emulsified asphalt mixed with water-based epoxy resin is much larger than that of ordinary emulsified asphalt and modified emulsified asphalt, indicating that water-based epoxy resin emulsified asphalt has high viscosity and toughness.

.
At 5℃, as the content of waterborne epoxy resin increases, the product shows a decreasing trend; while at 25℃ and 60℃, the product increases significantly at first, but when the content reaches 20%, the product tends to Steady
.
Therefore, the recommended content of water-based epoxy resin is 10%~20%
.

Rough Shear Test between Layers

In this study, AC-10 asphalt mixture was added on the surface of the roughened cement concrete to simulate the good relationship of the new pavement structure.
The epoxy resin content and the test temperature are consistent with the smooth shear test between layers.
The test results are shown in Figure 4.
5 shown
.

It can be seen from Figure 4 that the interlayer rough shear test and the interlayer smooth test have similar conclusions
.

(1) At low temperature, normal temperature and high temperature, the shear strength of water-based epoxy resin emulsified asphalt increases continuously with the increase of water-based epoxy resin content, and both are greater than the shear strength of ordinary emulsified asphalt and modified emulsified asphalt
.

(2) The shear limit displacement gradually decreases with the increase of the epoxy resin content, but both are greater than the displacement of ordinary emulsified asphalt and modified emulsified asphalt
.

(3) The temperature has a significant influence on the shear strength, and the shear strength decreases with the increase of temperature; and with the increase of temperature, the extreme displacement gradually increases
.

(4) Compared with the shear strength of the smooth interlayer specimen, the shear strength of the rough interlayer under the same test conditions is greater
.
Because in the case of rough interlayer, the shear strength is not only composed of the bonding force of the water-based epoxy resin emulsified asphalt, but also affected by the interlayer friction and squeezing effect
.

It can be seen from Fig.
5 that the product of the shear strength and the extreme displacement under the rough interlayer state is basically the same as the law when the interlayer is smooth
.
The two products of waterborne epoxy resin are much larger than ordinary emulsified asphalt and modified emulsified asphalt
.
At 5℃, the product decreases with the increase of the waterborne epoxy resin content; when the content is 20%~30%, the product changes significantly, and the product reaches the maximum value at 20%
.
At 25°C and 60°C, when the content reaches 10%, the product gradually stabilizes
.

Smooth pull test between layers

The differential deformation of the various structural layers of the pavement and the vehicle load result in the complicated force of the bonding layer
.
The bonding layer is not only subjected to horizontal shearing force, but also vertical pulling force
.
The results of the shear test are affected by the friction resistance between the layers and cannot be used to evaluate the self-adhesive properties of the interlayer materials.
A pullout test is required for the adhesive layer materials
.
In the test, the epoxy content and temperature variables are consistent with the interlayer smooth shear test, and the pull-out test results are shown in Figure 6
.

The following conclusions can be obtained from Figure 6
.

(1) The tensile strength of the adhesive layer material gradually increases with the increase of the water-based epoxy resin content
.
That is, the addition of water-based epoxy resin effectively improves the vertical bonding performance of the adhesive layer material
.

(2) The displacement of the drawing extreme value gradually decreases with the increase of the epoxy resin content, but both are larger than ordinary emulsified asphalt and modified emulsified asphalt, indicating that water-based epoxy resin can improve the vertical plastic properties of the adhesive layer material.
But with the increase of the waterborne epoxy resin content, the improvement effect gradually weakened
.
Therefore, the content of epoxy resin should be 10%~20%
.

(3) Temperature has a significant effect on the tensile strength of waterborne epoxy resin emulsified asphalt, and the tensile strength decreases with the increase of temperature
.

Rough pull test between layers

Figure 7 shows the results of the pull-out test when the interlayer is rough
.
It can be seen from Figure 7 that compared with the smooth tensile test between the layers, the test results of the waterborne epoxy resin emulsified asphalt with rough interlayers are not much different
.
This is because the tensile strength is mainly affected by the bonding force of the adhesive layer material, and has little relationship with the texture of the contact surface between layers
.

Concluding remarks

In this paper, Esso 90# matrix asphalt, water-based epoxy resin, polyvinyl alcohol, emulsifier and curing agent are used to prepare water-based epoxy resin emulsified asphalt interlayer bonding material, and the smooth and rough interlayer contact texture specimens are tested.
Shear test and pull test, draw the following conclusions
.

(1) Waterborne epoxy resin can improve the mechanical properties of emulsified asphalt, and its tensile and shear strength are greater than ordinary emulsified asphalt and 4% SBS modified emulsified asphalt
.
Therefore, as an adhesive layer material, waterborne epoxy resin emulsified asphalt has sufficient advantages
.

(2) The content of epoxy resin has a significant effect on the bonding performance of emulsified asphalt.
The shear and tensile strength of the adhesive layer material increases with the increase of its content, while the extreme displacement decreases with the increase of its content.

.
Therefore, the recommended content of epoxy resin is 10%~20%
.

(3) Temperature has a significant effect on the bonding performance of waterborne epoxy resin emulsified asphalt: as the temperature increases, the tensile and shear strength of the adhesive layer material decrease
.

(4) The contact between layers has a certain effect on the bonding performance of the waterborne epoxy resin emulsified asphalt: in the shear test, due to the roughness of the interlayer specimens affected by the friction resistance of the contact surface, the shear strength and the corresponding extreme displacement are both significant It is greater than the case where the interlayer is smooth; but the contact form between the layers has less influence on the tensile strength and the corresponding extreme displacement
.